Network topology formation

ABSTRACT

Systems and techniques are disclosed relating to wireless communications. The systems and techniques involve wireless communications wherein a module or communications device is configured to listen for a period of time for an incoming pilot signal from a remote terminal that exceeds a threshold power level for the purpose of acquiring such incoming pilot signal and operating under control of the remote terminal, and operating independently of the remote terminal if such pilot signal is not detected within the period of time, such independent operation including transmitting a pilot signal.

BACKGROUND

The present disclosure relates generally to wireless communications, andmore specifically, to various systems and techniques relating to theformation of ad-hoc networks.

In conventional wireless communications, an access network is generallyemployed to support communications for any number of mobile devices.These access networks are typically implemented with multiple fixed sitebase stations dispersed throughout a geographic region. The geographicregion is generally subdivided into smaller regions known as cells. Eachbase station may be configured to serve all mobile devices in itsrespective cell. As a result, the access network may not be easilyreconfigured to account for varying traffic demands across differentcellular regions.

In contrast to the conventional access network, ad-hoc networks aredynamic. An ad-hoc network may be formed when a number of wirelesscommunication devices, often referred to as terminals, decide to jointogether to form a network. Since terminals in ad-hoc networks operateas both hosts and routers, the network may be easily reconfigured tomeet existing traffic demands in a more efficient fashion. Moreover,ad-hoc networks do not require the infrastructure required byconventional access networks, making ad-hoc networks an attractivechoice for the future.

Ultra-Wideband (UWB) technology is an example of a communicationsmethodology that may be implemented with ad-hoc networks. UWB technologyprovides high speed communications over an extremely wide bandwidth. Atthe same time, UWB signals are transmitted in very short pulses thatconsume very little power. The output power of the UWB signal is so lowthat it looks like noise to other RF technologies, making it lessinterfering.

The topology of the ad-hoc network may have a direct impact onperformance. An ad-hoc network topology consisting solely ofuncoordinated communications between multiple terminals may be veryinefficient and result in high packet forwarding and routing overhead.Accordingly, a robust methodology for forming and maintaining a networktopology that is both efficient and low on overhead is desirable.

SUMMARY

In one aspect of the present invention, a module includes a receiverconfigured to listen for a period of time for an incoming pilot signalfrom a remote terminal that exceeds a threshold power level, and aprocessor configured to operate under control of the remote terminal ifthe receiver detects such incoming pilot signal within the time period,and operate independently of the remote terminal if such incoming pilotsignal is not detected by the receiver within the time period, suchindependent operation including enabling a pilot signal transmission.

In another aspect of the present invention, a method of communicationsincludes listening for a period of time for an incoming pilot signalfrom a remote terminal that exceeds a threshold power level for thepurpose of acquiring such incoming pilot signal and operating undercontrol of the remote terminal, determining that such incoming pilotsignal has not been acquired within the time period, and operatingindependently of the remote terminal, such independent operationincluding transmitting a pilot signal.

In yet another aspect of the present invention, a module includes meansfor listening for a period of time for an incoming pilot signal from aremote terminal that exceeds a threshold power level, means foroperating under control of the remote terminal if such incoming pilotsignal is detected within the time period, and means for operatingindependently of the remote terminal if such incoming pilot signal isnot detected within the time period, such independent operationincluding enabling a pilot signal transmission.

In a further aspect of the present invention, computer readable mediaembodying a program of instructions executable by a computer program maybe used to perform a method of communications, the method includinglistening for a period of time for an incoming pilot signal from aremote terminal that exceeds a threshold power level for the purpose ofacquiring such incoming pilot and operating under control of the remoteterminal, determining that such incoming pilot signal has not beenacquired within the time period, and operating independently of theremote terminal, such independent operation including transmitting apilot signal.

It is understood that other embodiments of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein various embodiments of the invention areshown and described by way of illustration. As will be realized, theinvention is capable of other and different embodiments and its severaldetails are capable of modification in various other respects, allwithout departing from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present invention are illustrated by way of example, andnot by way of limitation, in the accompanying drawings, wherein:

FIG. 1 is a conceptual diagram illustrating an example of a piconet;

FIG. 2 is a conceptual diagram illustrating an example of a piconethaving a peer-to-peer connection with an isolated terminal;

FIG. 3 is a conceptual diagram illustrating an example of twoneighboring piconets; and

FIG. 4 is a functional block diagram illustrating an example of aterminal capable of operating within a piconet.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentsin which the present invention may be practiced. Each embodimentdescribed in this disclosure is provided merely as an example orillustration of the present invention, and should not necessarily beconstrued as preferred or advantageous over other embodiments. Thedetailed description includes specific details for the purpose ofproviding a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without these specific details. In some instances,well-known structures and devices are shown in block diagram form inorder to avoid obscuring the concepts of the present invention. Acronymsand other descriptive terminology may be used merely for convenience andclarity and are not intended to limit the scope of the invention.

In the following detailed description, various aspects of the presentinvention may be described in the context of a UWB wirelesscommunications system. While these inventive aspects may be well suitedfor use with this application, those skilled in the art will readilyappreciate that these inventive aspects are likewise applicable for usein various other communication environments. Accordingly, any referenceto a UWB communications system is intended only to illustrate theinventive aspects, with the understanding that such inventive aspectshave a wide range of applications.

FIG. 1 illustrates an example of a network topology for a piconet in awireless communications system. A “piconet” is a collection ofcommunication devices or terminals connected using wireless technologyin an ad-hoc fashion. In at least one embodiment, each piconet has onemaster terminal and any number of member terminals slaved to the masterterminal. In FIG. 1, a piconet 102 is shown with a master terminal 104supporting communications between several member terminals 106. Themaster terminal 104 may be able to communicate with each of the memberterminals 106 in the piconet. The member terminals 106 may also be ableto directly communicate with one another under control of the masterterminal 104. As to be explained in greater detail below, each memberterminal 106 in the piconet 102 may also be able to directly communicatewith terminals outside the piconet.

The master terminal 104 may communicate with the member terminals 106using any multiple access scheme, such as time-division multiple access(TDMA), frequency-division multiple access (FDMA), code-divisionmultiple access (CDMA), or any other multiple access scheme. Toillustrate the various aspects of the present invention, the wirelesscommunications system shown in FIG. 1 will be described in the contextof a hybrid multiple access scheme employing both TDMA and CDMAtechnologies. Those skilled in the art will readily understand that thepresent invention is in no way limited to such multiple access schemes.

In TDMA communications, the master terminal 104 may use a periodic framestructure to communicate with the member terminals 106. This frame isoften referred to in the art as a medium access control (MAC) framebecause it is used to provide access to the communications medium forvarious channels. The frame may be any duration depending on theparticular application and overall design constraints. The frame may befurther divided into any number of time slots to support TDMAcommunications. For simplicity of discussion, a pilot signal broadcastby the master terminal 104 may be positioned in the first time slot ofeach frame. The exact location of the pilot signal in the frame willvary from system to system depending on the preferences of the skilledartisan.

The pilot signal may be an unmodulated spread spectrum signal, or anyother reference signal that is commonly used in traditional wirelesscommunication systems. In spread spectrum communications, apsuedo-random noise (PN) code unique to the master terminal 104 may beused to spread the pilot signal. Using a correlation process, the memberterminal 106 may search through all possible PN codes to acquire thestrongest pilot signal, such as the pilot signal broadcast by the masterterminal 104 in FIG. 1. The pilot signal may be used by the memberterminal 106 to synchronize to the master terminal 104. The pilot signalmay also be used by the member terminal 106 as a phase reference inorder to coherently demodulate communications from the master terminal104. The acquisition of a spread spectrum pilot signal is well known inthe art.

Once the member terminal 106 acquires the pilot signal, it maycommunicate with the master terminal 104 through various control andtraffic channels. One or more control channels may be time-divisionmultiplexed into any number of time slots in the frame. Since the timeslot assignments for the control channels are known by the memberterminals 106, a priori, the control channels may be accessed once themember terminal 106 is synchronized to the pilot signal. The controlchannels may be used by the master terminal 104 to scheduleintra-piconet communications. The term “intra-piconet communications”refers to communications between terminals residing in the same piconet.The master terminal 104 may assign one or more time slots in the frameto support intra-piconet communications. By way of example, a particulartransmitting terminal and a particular receiving member terminal may bescheduled to communicate during the n^(th) time slot in the frame. Thetransmitting terminal may use a portion of the n^(th) time slot in theframe to transmit a pilot signal, which may be used by the receivingterminal to coherently demodulate the communications. The masterterminal 104 may also grant transmit opportunities in a slot to anynumber of terminals 106 in its piconet using a CDMA scheme.

The master terminal 104 may also be used to manage high data ratecommunications. This may be achieved by allowing only those terminalsthat can support a minimum or threshold data rate with the masterterminal 104 to join the piconet 102. In UWB communication systems, forexample, a data rate of 1.2288 Mbps may be supported at a distance of30-100 meters depending on the propagation conditions. In these systems,the master terminal 104 may be configured to organize the piconet 102with member terminals 106 that can support a data rate of at least1.2288 Mbps. If higher data rates are desired, the range may be furtherrestricted. By way of example, data rates of 100 Mbps may be achieved inUWB systems at a range of 10 meters.

The member terminal 106 may be configured to determine whether it cansatisfy the minimum data rate requirements of the piconet by measuringthe link quality using the pilot signal broadcast from the masterterminal 104. As discussed in greater detail above, a terminal mayidentify the strongest pilot signal through a correlation process. Thelink quality may then be measured by computing thecarrier-to-interference (C/I) ratio from the strongest pilot signal bymeans well known in the art. Based on the C/I ratio computation, themember terminal 106 may then determine whether the minimum or thresholddata rate may be supported by means also well known in the art. If themember terminal 106 determines that the minimum or threshold data ratemay be supported, it may attempt to join the piconet 102 by registeringwith the master terminal 104 over the appropriate control channel.

A member terminal 106, due to the availability of line power or otherpower source, or larger stored power (battery), or due to administrativestatus may be a preferred master terminal based on these enhancedcapabilities. After a member terminal 106 with enhanced capabilitiesregisters with the piconet master 104, it may attempt to gain control ofthe piconet through an exchange of signaling messages. If the piconetmaster 104 is not itself a preferred piconet master, it may surrendercontrol to the member terminal 106. In the process of surrenderingcontrol, the piconet master 104 may transfer its current state (e.g.on-going reservations, bridge terminals, etc) to the member terminal106. After the state transfer is complete, the piconet master may stoptransmitting its pilot signal, and the member terminal 106 may becomethe new piconet master by transmitting its pilot signal. Terminalsregistered with the former piconet master 104 may re-acquire andre-register with the new piconet master 106. In at least one embodiment,communications from the other member terminals 106 may be redirected tothe new piconet master 106 before it gains control of the piconet.

In some instances, a terminal may be unable to find a pilot signal ofsufficient signal strength to support the minimum or threshold data rateafter a predetermined amount of time. This may result from any number ofreasons. By way of example, the terminal may be too far from the masterterminal. Alternatively, the propagation environment may be insufficientto support the requisite data rate. In either case, the terminal may beunable to join an existing piconet. FIG. 2 illustrates an example of anetwork topology with a wireless terminal 202 unable to join the piconet102 of FIG. 1.

Referring to FIG. 2, if the terminal 202 is far away from the masterterminal 104, the terminal 202 may determine from the C/I ratio computedfrom the pilot signal broadcasted by the master terminal 104 that theminimum or threshold data rate cannot be sustained, or the terminal 202may be unable to decode the pilot signal from master terminal 104. As aresult, the terminal 202 may begin operating as an isolated terminalindependent of the piconet 102 by transmitting its own pilot signal. Ina manner to be described in greater detail shortly, the isolatedterminal 202 may engage in peer-to-peer communications with any memberterminal 106 in the piconet 102 through a bridge terminal. “Peer-to-peercommunications” refers to those communications between terminals thatare not controlled by a master terminal. As discussed below, the masterterminal may in fact set aside time in the piconet schedule toaccommodate peer-to-peer transmissions from the bridge terminal.

The master terminal 104 may designate any number of member terminals 106as piconet edge terminals, such as member terminal 106 a. Thedesignation of piconet edge terminals may be based on feedback from thevarious member terminals 106. By way of example, the computed C/I ratiofrom each member terminal 106 may provide a rough indication of thosemember terminals located at the edge of the piconet 102. The piconetedge terminal 106 a may be assigned the task of listening for pilotsignals from isolated terminals. When a piconet edge terminal 106 adetects a pilot signal from an isolated terminal, such as the isolatedterminal 202 shown in FIG. 2, then the piconet edge terminal 106 a mayestablish a-peer-to-peer connection with the isolated terminal 202.Although peer-to-peer communications in their purest sense are random,the master terminal 104 may exercise some control over thesecommunications by scheduling the transmission and receiving times of thepiconet edge terminal 106 a. To reduce interference, the master terminal104 may schedule intra-piconet communications and peer-to-peercommunications by the piconet edge terminals at different times.Communications between the isolated terminal 202 and any member terminal106 in the piconet 102 may be supported through the bridge terminal 106a.

The isolated terminal 202 may become the master terminal for a newpiconet On power up, terminals that are able to receive the pilot signalbroadcast from the isolated terminal 202 with sufficient strength mayattempt to acquire that pilot signal and join the piconet of thisisolated terminal. FIG. 3 illustrates an example of a network topologyof this kind. The first piconet 102 is the same piconet described inconnection with FIG. 1 with its master terminal 104 supporting severalmember terminals 106. The isolated terminal 202 described in connectionwith FIG. 2 has become the master terminal for a second piconet 302. Themaster terminal 202 in the second piconet 302 may be used to supportmultiple member terminals 306.

Using feedback from the various member terminals 306, the masterterminal 202 in the second piconet 302 may designate one or more memberterminals 306 as piconet edge terminals, such as member terminal 306 a.As described in greater detail above, the master terminal 104 in thefirst piconet 102 may also designate one or more member terminals 106 aspiconet edge terminals, such as member terminal 106 a. In addition tolistening for pilot signals broadcast from isolated terminals, eachpiconet edge terminal may also listen for pilot signals broadcast fromother neighboring piconet master terminals. By way of example, when thepiconet edge terminal 106 a from the first piconet 102 detects the pilotsignal broadcast from the master terminal 202 in the second piconet 302,it may establish a connection with that master terminal 202. The masterterminal 202 may maintain that connection, or alternatively, assign apiconet edge terminal 306 a to maintain the connection, in the secondpiconet 302. The piconet edge terminals 106 a and 306 a may be referredto as bridge terminals. Communications between a terminal in the firstpiconet 102 and a terminal in the second piconet 302 may be supportedthrough the bridge terminals 106 a and 306 a.

The time period for which a terminal searches for a pilot signal from anexisting piconet master before starting to transmit its own pilot signalmay vary depending on the specific communications application and theoverall design constraints. In one embodiment, the search time may be afunction of the terminals enhanced capabilities. Terminals with enhancedcapabilities may use a shorter search time before starting to transmit apilot signal.

Returning to FIG. 1, the master terminal 104 may be used to manage thenumber of member terminals 106 that may join the piconet 102. In thisembodiment, the master terminal 104 maintains a table of registeredmember terminals 106 in memory. The number of registered terminalsstored in memory may be compared to a threshold number. The thresholdnumber may be predetermined at the factory, or alternatively dynamicallyadjusted depending on the communications environment and other relatedfactors. In any event, once the number of registered member terminals106 reaches the threshold, the master terminal 104 may reduce the powerlevel of the pilot signal. When the power level of the pilot signal isreduced, certain member terminals farthest from the master terminal 104may no longer be able to receive the pilot signal at a level that isable to sustain the minimum or threshold data rate. These terminals maydrop their membership in the piconet 102 and search for an alternativepiconet master terminal. If one or more of these terminals is unable tofind a suitable piconet master terminal, it may begin operating as anisolated terminal by transmitting its own pilot signal. It may remain anisolated terminal for peer-to-peer communications until such time thatone or more wireless devices register with it, thereby forming a newpiconet.

FIG. 4 is a conceptual block diagram illustrating one possibleconfiguration of a terminal. As those skilled in the art willappreciate, the precise configuration of the terminal may vary dependingon the specific application and the overall design constraints. For thepurposes of clarity and completeness, the various inventive conceptswill be described in the context of a UWB terminal with spread-spectrumcapability, however, such inventive concepts are likewise suitable foruse in various other communication devices. Accordingly any reference toa spread-spectrum UWB terminal is intended only to illustrate thevarious aspects of the invention, with the understanding that suchaspects have a wide range of applications.

The terminal may be implemented with a front end transceiver 402 coupledto an antenna 404. A baseband processor 406 may be used to providesignal processing as well as executive control and overall systemmanagement functions. The terminal may also include various userinterfaces 408 such as a keypad, display, ringer, vibrator, audiospeaker, microphone, and the like.

The transceiver 402 may include a receiver 410. The receiver 410 may beused to convert an analog waveform at RF frequencies received from theantenna 404 to a digital baseband signal. The receiver 410 may also beused to provide various gain and filter functions to improve overallperformance.

The transceiver 402 may also include a transmitter 412. The transmitter412 may be used to convert a digital baseband signal from the basebandprocessor 406 to an analog waveform at RF frequencies for over the airtransmission through the antenna 404. The transmitter 412 may also beused to shape the waveform and provide gain adjustment to supportvarious power control functions that are well known in the art.

The baseband processor 406 may include a modem 413 which providesvarious signal processing functions such as pilot signal acquisition,time synchronization, frequency tracking, spread-spectrum processing,modulation and demodulation functions, and forward error correction. Thesignal processing functions performed by the modem 413 may be controlledand coordinated by a controller 414.

When power is initially applied to the terminal, the controller 414 maybe used to invoke various signal processing functions including a searchby the modem 413 through the digital baseband signal output from thereceiver 410 for a spread-spectrum pilot signal broadcast from a masterterminal. This may be accomplished through the combined efforts of asearcher 416 and PN code generator 418. The PN code generator 418 may beused to sequence through all possible PN codes as the searcher attemptsto align each code generated by the PN code generator 418 with aspread-spectrum pilot signal in the digital baseband signal. If thesearcher 416 is successful and locates a pilot signal within apredetermined time established by the controller 412, then the basebandprocessor 406 may be configured to slave its operation to the masterterminal. As discussed earlier, the predetermined time may be set as afunction of the terminal's capabilities. If the searcher 416 detectsmultiple pilot signals, it may select the strongest pilot signal toacquire and slave its operation to.

As discussed in detail earlier, the acquisition of the pilot signal maydepend on the minimum data rate requirements for the piconet. Thesearcher 416 may be used to ensure that this condition is met bycomputing and evaluating a parameter from the pilot signal indicative oflink quality. By way of example, the searcher 416 may be configured tocompute the C/I ratio from the pilot signal and compare the resultantcomputation to a threshold. Using this method, the strongest pilotsignal that exceeds the threshold may be acquired.

Once the pilot signal for a master terminal is acquired, the codegenerated by the PN code generator 418 and used by the searcher 416 tocorrelate the pilot signal may be provided to a modulator 420. This codeis a locally generated replica of the unique PN code assigned to themaster terminal. The modulator 420 may use the code to spread variouscommunications to the master terminal including registration informationgenerated by the controller 414, C/I ratio computed by the searcher 416,and any other signaling information such as might be the case if theterminal is attempting to gain control of the piconet because it is apreferred master terminal. This information may be channelized by usinga time-division multiplexing scheme or TDMA scheme using conventionalcontention and reservation techniques, or alternatively, orthogonalcodes, such as Walsh codes. In any event, this spread-spectruminformation may be released to the transmitter 412 in the appropriatecontrol channel time slots in the frame.

The same code provided to the modulator 420 may also be provided to ademodulator 422 to recover information on one or more control channels.The recovered information may contain various commands andacknowledgements for the controller 414. By way of example, therecovered information may contain an acknowledgement indicating that theterminal has been successfully registered with the master terminal, orthat the master terminal will relinquish control of the piconet to thebaseband processor 406.

Another example of information that may be recovered by the demodulator422 from the control channels is a command instructing the terminal tolisten for pilot signals outside the piconet, as the case might be ifthe terminal is at the edge of the piconet. In response, the controller414 may enable the searcher 416 to perform this function. The results ofthe search may be reported back to the master terminal using themodulator 420 to spread the results with the locally generated replicaof the PN code for the master terminal.

Scheduling information may also be recovered by the demodulator 422 fromthe control channels and provided to the controller 414. The schedulinginformation may include transmission and reception times for theterminal. If the communications are spread-spectrum, the schedulinginformation may also include PN code assignments for each transmissionand reception The controller 414 may use this scheduling information tomanage the baseband processor 406.

Returning for a moment to the pilot signal acquisition process onpower-up, the controller 414 may be configured to disable the searcher416 if a pilot signal of suitable strength cannot be acquired within apredetermined time. Once the searcher 416 is disabled, the controller414 may configure the baseband processor 404 as an isolated or masterterminal. In this configuration, the controller 414 may be used toenable a pilot signal generator 423. The pilot generator 423 may be usedto provide a pilot signal to the modulator 420. The modulator 420 mayspread the pilot signal with a PN code unique to the terminal. Thespread-spectrum pilot signal may then be provided to the transmitter 412for over-the-air broadcast via the antenna 404.

The controller 414 may control the power level of the pilot signal tomanage the size of the piconet. This may be achieved in a variety offashions. By way of example, the controller 414 may be configured tomaintain a list of all registered terminals in memory. As theregistrations change due to the mobility of the member terminals, thecontroller 414 may be configured to periodically compare the number ofregistered terminals to a threshold. The threshold may be set to limitthe amount of traffic in the piconet to avoid adverse effects on timesensitive communications. If the number of terminal registrations exceedthe threshold, then the controller 414 may reduce the power of the pilotsignal at the transmitter 412. This should cause terminals at the edgeof the piconet to drop their membership because they can no longer meetthe minimum data rate requirements for the piconet.

The controller 414 may also be used to perform various controlfunctions. By way of example, the controller 414 may engage in two-waycommunications with its member terminals to complete the registrationprocess using one or more control channels. Piconet edge terminalassignments based on the C/I ratio computations of the individual memberterminals and scheduling assignments may also be made by the controller.The information on the control channels may be spread with the terminalPN code by the modulator 420 for transmissions, and recovered using theterminal PN code by the demodulator 422 upon receipt.

Whether the baseband processor 406 is configured as a master or memberterminal of a piconet, the manner in which traffic communications arehandled are fundamentally the same. A buffer 424 may be used to storedata from one or more of the various user interfaces 408, such as datafrom the keypad or voice from the microphone. The controller 414 may beused to release the data from the buffer 424 at the scheduled time. Thedata may be provided to an encoder 426 for convolutional coding andinterleaving. The encoded data may be provided to the modulator 420 formodulation and spreading with the appropriate PN code assigned to thattransmission. The resultant data may then be provided to the transmitter412 for over-the-air transmission via the antenna 404.

The demodulator 422 may use a rake receiver to recover data transmittedby another terminal. Rake receivers are well known in the art. The rakereceiver uses independent fading of resolvable multi-paths to achievediversity gain. Specifically, the rake receiver may be configured toprocess one or more multipaths from the transmitting terminal. Eachmultipath may be fed into a separate finger processor to perform PN codedispreading. The searcher 416 may use the pilot embedded in the trafficsignal to identify strong multipath arrivals and assign the fingers inthe rake receiver. The result from each finger processor may then becombined to recover the data. The recovered data may be demodulated andprovided to a decoder 428 for de-interleaving, decoding and frame-checkfunctions. The decoded data may then be provided to one or more of thevarious user interfaces 420, such as the display or audio speaker.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The methods or algorithms described in connection with the embodimentsdisclosed herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. A storagemedium may be coupled to the processor such that the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor. Theprocessor and the storage medium may reside in an ASIC. The ASIC mayreside in the subscriber station, or elsewhere. In the alternative, theprocessor and the storage medium may reside as discrete components inthe subscriber station, or elsewhere in an access network.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

1. A module, comprising: a receiver configured to listen for a period oftime for an incoming pilot signal from a remote terminal that exceeds athreshold power level; and a processor configured to operate undercontrol of the remote terminal if the receiver detects such incomingpilot signal within the time period, and operate independently of theremote terminal if such incoming pilot signal is not detected by thereceiver within the time period, such independent operation includingenabling a pilot signal transmission.
 2. The module of claim 1 whereinthe processor is further configured to establish a communications linkwith a second remote terminal that acquires the transmitted pilotsignal.
 3. The module of claim 1 wherein the processor is furtherconfigured to register each of a plurality of second remote terminalsthat acquire the transmitted pilot signal.
 4. The module of claim 3wherein the processor is further configured to manage the number ofterminal registrations.
 5. The module of claim 4 wherein the processoris further configured to manage the number of terminal registrations byadjusting the power level of the pilot signal transmission.
 6. Themodule of claim 3 wherein the processor is further configured to receivefeedback from each of the registered terminals and designate one or moreof the registered terminals to support communications with unregisteredterminals based on the feedback.
 7. The module of claim 6 wherein thefeedback provided by each of the registered terminals is an indicator ofthe transmitted pilot signal strength measured at its respectiveregistered terminals.
 8. The module of claim 1 wherein the processor isfurther configured to receive a request to communicate from anunregistered terminal and assign one of the registered terminals tocommunicate with the unregistered terminal.
 9. The module of claim 1wherein the processor is further configured to set the threshold powerlevel as a function of a minimum data rate that can be supported withthe remote terminal.
 10. The module of claim 1 wherein the processor isfurther configured to register with the remote terminal if the receiverdetects such incoming pilot signal within the time period.
 11. Themodule of claim 10 wherein the receiver is further configured to listenfor a second incoming pilot signal from a second remote terminal notregistered with the remote terminal, and wherein the processor isfurther configured to establish a communications link with the secondremote terminal if the receiver detects the second incoming pilotsignal.
 12. The module of claim 11 wherein the processor is furtherconfigured to schedule the receiver to listen for the second incomingpilot signal under control of the remote terminal.
 13. The module ofclaim 10 wherein the processor is further configured to establish acommunications link with a second remote terminal not registered withthe remote terminal under direction of the remote terminal.
 14. Themodule of claim 1 wherein the period of time the receiver listens forsuch incoming pilot signal is a function of the capabilities of themodule.
 15. A method of communications, comprising: listening for aperiod of time for an incoming pilot signal from a remote terminal thatexceeds a threshold power level for the purpose of acquiring suchincoming pilot signal and operating under control of the remoteterminal; determining that such incoming pilot signal has not beenacquired within the time period; and operating independently of theremote terminal, such independent operation including transmitting apilot signal.
 16. The method of claim 15 further comprising establishinga communications link with a second remote terminal.
 17. The method ofclaim 15 further comprising registering each of a plurality of secondterminals.
 18. The method of claim 17 further comprising managing thenumber of terminal registrations.
 19. The method of claim 18 wherein themanagement of the number of terminal registrations comprises adjustingthe power level of the transmitted pilot signal.
 20. The method of claim17 further comprising receiving feedback from each of the registeredterminals and designating one or more of the registered terminals asedge terminals to support communications with unregistered terminalsbased on the feedback.
 21. The method of claim 20 wherein the feedbackprovided by each of the registered second terminals is an indicator ofthe pilot signal strength measured at its respective registeredterminal.
 22. The method of claim 15 further comprising receiving arequest to communicate from an unregistered terminal and assigning oneof the registered terminals to communicate with the unregisteredterminal.
 23. A module, comprising: means for listening for a period oftime for an incoming pilot signal from a remote terminal that exceeds athreshold power level; means for operating under control of the remoteterminal if such incoming pilot signal is detected within the timeperiod; and means for operating independently of the remote terminal ifsuch incoming pilot signal is not detected within the time period, suchindependent operation including enabling a pilot signal transmission.24. The module of claim 23 further comprising means for registering aplurality of second remote terminals that acquire the transmitted pilotsignal.
 25. The module of claim 24 further comprising means for managingthe number of terminal registrations by adjusting the power level of thepilot signal transmission.
 26. The module of claim 23 further comprisingmeans for setting the threshold power level as a function of a minimumdata rate that can be supported with the remote terminal.
 27. Computerreadable media embodying a program of instructions executable by acomputer program to perform a method of communications, the methodcomprising: listening for a period of time for an incoming pilot signalfrom a remote terminal that exceeds a threshold power level for thepurpose of acquiring such incoming pilot and operating under control ofthe remote terminal; determining that such incoming pilot signal has notbeen acquired within the time period; and operating independently of theremote terminal, such independent operation including transmitting apilot signal.
 28. The computer readable media of claim 27 wherein themethod further comprises registering with a plurality of second remoteterminals that acquire the transmitted pilot signal
 29. The computerreadable media of claim 28 wherein the method further comprises managingthe number of terminal registrations by adjusting the power level of thepilot signal transmission.
 30. The computer readable media of claim 27wherein the method further comprises setting the threshold power levelas a function of a minimum data rate that can be supported with theremote terminal.
 31. A method of communications, comprising: listeningfor a period of time to acquire an incoming pilot signal from a remoteterminal; determining that such incoming pilot signal has been acquiredwithin the time period; exchanging signaling messages with the remoteterminal once such incoming pilot signal has been acquired; enabling apilot signal transmission for the purpose of operating independently ofthe remote terminal; and registering a plurality of second remoteterminals that acquire the transmitted pilot signal, the second remoteterminals being previously registered with the remote terminal prior tothe exchange of signaling messages.
 32. A method of communications,comprising: a receiver configured to listen for a period of time toacquire an incoming pilot signal from a remote terminal; and a processorconfigured to acquire such incoming signal if the receiver detects suchincoming pilot signal within the time period, exchange signalingmessages with the remote terminal once such incoming pilot signal hasbeen acquired, enable a pilot signal transmission for the purpose ofoperating independently of the remote terminal, and register a pluralityof second remote terminals that acquire the transmitted pilot signal,the second remote terminals being previously registered with the remoteterminal prior to the exchange of signaling messages.